title: Iridescence and spectral filtering of the gyroid-type photonic crystals in Parides sesostris wing scales.
abstract: The cover scales on the wing of the Emerald-patched Cattleheart butterfly, Parides sesostris, contain gyroid-type biological photonic crystals that brightly reflect green light. A pigment, which absorbs maximally at approximately 395 nm, is immersed predominantly throughout the elaborate upper lamina. This pigment acts as a long-pass filter shaping the reflectance spectrum of the underlying photonic crystals. The additional effect of the filtering is that the spatial distribution of the scale reflectance is approximately angle-independent, leading to a stable wing pattern contrast. The spectral tuning of the original reflectance is verified by photonic band structure modelling.
authors.affiliation: Computational Physics, Zernike Institute for Advanced Materials , University of Groningen , 9747 AG Groningen , The Netherlands.
authors.forename: Bodo D
authors.initials: BD
authors.lastname: Wilts
authors.forename: Kristel
authors.initials: K
authors.lastname: Michielsen
authors.forename: Hans
authors.initials: H
authors.lastname: De Raedt
authors.forename: Doekele G
authors.initials: DG
authors.lastname: Stavenga
keywords: Papilionidae; biomaterials; iridescence; optical filtering; photonic crystal